基质细胞衍化因子-1对人内皮祖细胞迁移的影响

目的 探讨基质细胞衍化因子-1对内皮祖细胞迁移的影响.方法 用流式细胞仪、RT-PCR、内皮功能实验鉴定内皮祖细胞,检测其CXCR4受体表达和迁移功能.结果 培养单个核细胞7 d,CD34阳性率为36.3%±23.8%,CD133为19.7%±10.3%,双阳性率为18.6%±10.7%,表达KDR基因,>90%的细胞吸收DiI-ac LDL和FITC-UEA-1.CXCR4表达率为74.8%,对照组、基质细胞衍化因子-1浓度为10、20和50μg/L时,细胞迁移数分别为3.5、7.4、24.9和28.0个.各组浓度的细胞迁移数均显著高于对照组(P<0.01),20μg/L组显著高于10μg/L组、50μg/L组显著高于10μg/L组(P<0.01),50μg/L组显著高于20μg/L组(P<0.05).结论 (1)从外周血途径分离、培养和扩增获得内皮祖细胞,表达CXCR4受体;(2)内皮祖细胞可在基质细胞衍化因子-1的趋化作用下迁移,且与其浓度呈正相关.     

Cyclic variability of stromal cell-derived factor-1 and endothelial progenitor cells during the menstrual cycle

The endometrium goes through a unique cycle of physiological angiogenesis during the normal menstrual cycle (MC). We studied whether there is a correlation between endothelial progenitor cells (EPCs) and plasma and endometrial levels of angiogenic growth factors during the MC. Ten healthy, regularly menstruating women provided blood samples and another 16 supplied endometrial biopsies. Blood samples were obtained over a single MC: twice in the proliferative and once in the secretory phase and at ovulation. Endometrial biopsies were provided in the proliferative or in the secretory phase. We assessed plasma levels of vascular endothelial and fibroblast growth factors, granulocyte and granulocyte-macrophage colony-stimulating factors and stromal cell-derived factor-1 (SDF-1) by ELISA; EPCs by a colony-forming unit (CFU) assay; immunostaining for endometrial SDF-1 by computer-assisted software; and endothelial cell (EC) markers by flow cytometry. In the proliferative phase, SDF-1 levels were significantly higher than during the secretory phase. EPC-CFUs correlated negatively to SDF-1 levels. Endometrial SDF-1 expression tended to be higher in the secretory than in the proliferative phase. Furthermore, vascular endothelial growth factor receptors and Tie-2 EPCs showed a cyclic pattern over the MC. Our results point to SDF-1 as a novel mediator of EPC trafficking during the MC.     

Long-term hematopoietic stem cells require stromal cell-derived factor-1 for colonizing bone marrow during ontogeny

The physiological role of SDF-1 on hematopoietic stem cells (HSCs) remains elusive. We show that colonization of bone marrow by HSCs in addition to myeloid cells is severely impaired in SDF-1(-/-) embryos by a long-term repopulation assay. Colonization of spleen by HSCs was also affected, but to a lesser extent. Enforced expression of SDF-1 under the control of vascular-specific Tie-2 regulatory sequences could completely rescue the reduction of HSCs but not myeloid cells in SDF-1(-/-) bone marrow. SDF-1 was detected in the vicinity of the vascular endothelial cells in fetal bone marrow. SDF-1 plays a critical role in colonization of bone marrow by HSCs and myeloid cells during ontogeny, and the mechanisms by which SDF-1 functions are distinct between HSCs and myeloid cells.     

基质细胞衍化因子1与内皮祖细胞协同促血管新生

背景：动脉硬化性疾病的发病基础是内皮功能失调,循环中的内皮祖细胞数量和功能均下降,自身血管新生能力不足,单纯干细胞移植的疗效尚不确实,应用细胞因子以及基因修饰干细胞等方法是重要的研究方向。 目的：观察基质细胞衍化因子1对内皮祖细胞移植促血管新生的影响。 方法：制备20只单侧后肢缺血裸鼠模型,随机分为4组,分别给予静脉注射内皮祖细胞和肌肉注射基质细胞衍化因子1、静脉注射内皮祖细胞、局部肌肉注射基质细胞衍化因子1、肌肉注射培养液。造模后观察动物缺血后肢的皮温及存活情况,检测毛细血管/肌纤维比值、CD31和内皮型一氧化氮合酶表达情况。 结果与结论：荧光标记内皮祖细胞移植后整合至缺血后肢肌肉。20只裸鼠死亡2只。联合治疗组、内皮祖细胞组、基质细胞衍化因子1组和空白对照组患肢保存率分别为80%,75%,20%和0。毛细血管/肌纤维比值检测结果显示,联合治疗组和内皮祖细胞组高于空白对照组(P < 0.01),联合治疗组高于内皮祖细胞组、内皮祖细胞组高于基质细胞衍化因子1组(P < 0.05)。血管密度检测结果显示,联合治疗组、内皮祖细胞组大于空白对照组(P < 0.01),基质细胞衍化因子1组大于空白对照组(P < 0.05),联合治疗组大于内皮祖细胞组、内皮祖细胞组大于基质细胞衍化因子1组(P < 0.05)。联合治疗组和内皮祖细胞组缺血肌肉内皮型一氧化氮合酶阳性率分别为73.33%和53.33%(P > 0.05)。提示内皮祖细胞可定向迁移至缺血组织,内皮祖细胞移植能促进治疗性血管新生,基质细胞衍化因子1可增强这一作用,内皮型一氧化氮合酶参与了内皮祖细胞促血管新生的过程。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

基质细胞衍生因子受体在造血干/祖细胞宫内移植中的作用

目的探讨基质细胞衍生因子受体(CXCR4)在造血干/祖细胞(HSC)宫内移植归巢中的作用。方法分离人脐血CD34+细胞,用流式细胞仪检测SCF、IL-6处理前后细胞表面CXCR4(CD184)的表达及在Transwell板中的迁移率。在BALB/c胎鼠孕13～14d期间,经胎鼠腹腔注射经不同处理的CD34+细胞,胎鼠出生1个月后取骨髓,用流式细胞仪检测人CD45细胞。结果预处理后表达CD184的CD34+细胞的百分数由原来的9.58%±1.56%上升为19.32%±3.64%。CD34+/CXCR4high细胞迁移率显著增高,但迁移作用可以被antiCXCR4mAb和PTX明显抑制。SCF和IL-6预处理组胎鼠人CD45细胞阳性率显著高于其他组。抗CXCR4抗体或PTX预处理组人CD45细胞检出率显著降低。结论增加CD34+细胞CXCR4的表达有助于宫内移植HSC的归巢,HSC宫内移植归巢过程依赖CXCR4受体,SDF-1/CXCR4调节信号通过Gi蛋白进行跨膜传导。     

Statin and stromal cell-derived factor-1 additively promote angiogenesis by enhancement of progenitor cells incorporation into new vessels

Angiogenesis requires the mobilization of progenitor cells from the bone marrow and homing of progenitor cells to ischemic tissue. Statins facilitate the former, and the chemokine stromal cell-derived factor-1 (SDF-1) enhances the latter. Their combined influence on angiogenesis was studied in vivo in the ischemic hindlimb C57BL/6 mouse model. The ischemic to non-ischemic perfusion ratio increased from 0.29 +/- 0.02 immediately after femoral excision to 0.51 +/- 0.10 three weeks after the surgery in the mice treated with either fluvastatin or SDF-1 alone, which is significantly better than the control (0.38 +/- 0.05, p < .05, n = 6). The combined use of fluvastatin and SDF-1 further improved the reperfusion ratio (0.62 +/- 0.08, p < .05). More cell proliferation, less apoptosis, enhanced bone marrow-derived endothelial progenitor cell (EPC) incorporation and higher capillary density were observed in ischemic tissue treated with both statin and SDF-1. In vitro mono-treatment with either fluvastatin (100 nM) or SDF-1 (100 ng/ml) facilitated EPC proliferation and migration, inhibited EPC apoptosis, enhanced expression of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9), and increased Akt phosphorylation and nitric oxide production. These effects were significantly augmented by the two agents together and ablated by inhibitors of either Akt or nitric oxide synthase (NOS). In conclusion, statin and SDF-1 additively enhance progenitor cell migration and proliferation and down-regulate EPC apoptosis, resulting in improved reperfusion via activation of the Akt/NOS pathway and up-regulation of MMP-2 and MMP-9 expression.     

The neurotransmitter GABA is a potent inhibitor of the stromal cell-derived factor-1alpha induced migration of adult CD133+ hematopoietic stem and progenitor cells

The ability of hematopoietic stem and progenitor cells (HSPCs) to migrate is a prerequisite for bone marrow homing and tissue regeneration processes. Induction of HSPC migration is chiefly directed by stromal cell-derived factor-1alpha (SDF-1alpha). Considerably less is known about factors that terminate HSPC migration. Adult CD133(+) HSPCs were isolated from mobilized peripheral blood by immunomagnetic separation. Cell migration was assessed using the three-dimensional collagen matrix migration assay, which allows detailed migration analysis on a cell population and single-cell level. The SDF-1alpha-induced locomotory activity of CD133(+) cells was efficiently blocked by the neurotransmitter gamma-aminobutyric acid (GABA). GABA signaling was effected via the GABA(B)-receptor. This was verified by flow cytometry and cell migration studies using the specific GABA(A)-receptor and GABA(B)-receptor agonists isoguvacine and baclofen, respectively. Baclofen blocked SDF-1alpha-induced migration of CD133(+) cells. Flow cytometry-based calcium measurements revealed that GABA inhibits the SDF-1alpha-induced migration of CD133(+) cells by blocking the SDF-1alpha-induced calcium influx. Similar results were obtained with the specific calcium-release-activated calcium (CRAC) channel inhibitor BTP-2, which both blocked the SDF-1alpha-induced calcium influx and migration of CD133(+) cells. These results suggest that GABA(B)-receptor signaling modulates the activity of CRAC channels, whereby the mechanism in detail remains unclear. In summary, the neurotransmitter GABA is a potent blocker of the SDF-1alpha-induced migration of CD133(+) HSPCs from mobilized peripheral blood.     

Stromal cell-derived factor-1/CXCL12 selectively counteracts inhibitory effects of myelosuppressive chemokines on hematopoietic progenitor cell proliferation in vitro

A variety of cytokines and chemokines exert potent myelosuppressive effects that play a role in the maintenance of hematopoiesis, which, if unchecked, may result in pathological impairment of blood cell production. Processes that modulate these myelosuppressive effects are not well defined. Here we demonstrate that stromal cell-derived factor-1 (SDF-1/CXCL12), known for its ability to attract and to promote survival of hematopoietic progenitor cells (HPCs) and stem cells, blocks the effects of a broad range of myelosuppressive chemokines on proliferation of HPCs in vitro. The regulatory effects of SDF/CXCL12 on colony formation by mouse bone marrow granulocyte-macrophage (CFUGM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells were assessed. These cells were stimulated to proliferate by combinations of growth factors, such that responses of immature HPCs could be assessed. SDF-1/CXCL12 potently blocked myelosuppressive responses induced by CCL2/MCP-1, CCL3/MIP-1alpha, CCL19/CKbeta-11, CCL25/TECK, CXCL4/PF4, CXCL8/IL-8, CXCL10/IP-10, and XCL1/Lymphotactin. However, SDF/CDL12 did not influence myelosuppression induced by tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, transforming growth factor (TGF)-beta or the iron-binding proteins H-ferritin or lactoferrin (LF). LF, previously shown to suppress release of growth factors, is shown here to also suppress proliferation of immature subsets of HPCs. HPCs from marrows of mice expressing an SDF-1/CXCL12 transgene were insensitive to inhibition by SDF/CXCL12-sensitive myelosuppressive chemokines, but not to SDF/CCL12-insensitive cytokines (TNF-alpha, IFN-gamma, TGF-beta, H-Ferritin, or LF). Thus, SDF-1/CXCL12 differentially and selectively regulates suppression of HPC proliferation by chemokines. These effects may counter myelosuppressive effects of certain chemokines in vivo, where proliferation of HPCs must be sustained.     

低氧诱导肺动脉内皮细胞间质细胞衍生因子-1的表达及其调控机制

肺血管重塑（PVR）是低氧性肺动脉高压持续且难以逆转的主要原因,其主要病变表现为肺动脉壁细胞增多,但其来源和机制仍不清楚。研究表明骨髓和外周血中存在血管壁细胞的祖细胞,并且参与了PVR的形成。间质细胞衍生因子-1（SDF-1）是特异性介导干细胞归巢至骨髓,介导祖细胞归巢至损伤或缺血组织的关键因子。SDF-1表达在这些部位的血管内皮细胞,而低氧是这些部位的微环境特征,也是诱导SDF-1表达的主要原因。低氧诱导因子-1α（HIF-1α）是特异性介导细胞低氧反应的关键因子,直接调控脐静脉内皮细胞SDF-1基因的表达㈨。我们旨在探讨低氧对肺动脉内皮细胞SDF-1表达的影响及HIF-1α对其表达的调控作用。     

软骨损伤后基质细胞衍生因子1的表达

背景：研究表明基质细胞衍生因子1对骨髓间充质干细胞的迁移、聚集有影响。 目的：观察软骨损伤后不同时间损伤修复区组织基质细胞衍生因子1的表达以及与骨髓间充质干细胞迁移的关系。 方法：建立兔软骨损伤模型,分别于建模后2,5,7,10,14,28 d取损伤灶及边缘区组织,检测基质细胞衍生因子1表达和体外细胞迁移实验,观察基质细胞衍生因子1对骨髓间充质干细胞、软骨细胞的迁移影响。 结果与结论：基质细胞衍生因子1的表达呈现出时间变化的趋势,软骨损伤后第7天达到高峰(P < 0.05)。体内移植的骨髓间充质干细胞主要聚集在软骨损伤灶周围,但在封闭CXC趋化因子受体4后,此聚集现象逐渐减弱(P < 0.05)。结果证实,局部组织中基质细胞衍生因子1的表达在软骨损伤早期明显升高,对骨髓间充质干细胞向软骨损伤修复区迁移有重要作用。     

A stromal cell-derived membrane protein that supports hematopoietic stem cells

Hematopoietic stem cells cannot be maintained in vitro without stromal cells, even if they are provided with growth factors, and it is likely that supportive cells in the bone marrow express membrane or secreted proteins that maintain hematopoiesis. Here we show that mKirre, a mammalian homolog of the gene kirre of Drosophila melanogaster, encodes a type Ia membrane protein that is involved in the hematopoietic supportive capacity of OP9 mouse stromal cells. Repressing mKirre expression with a short interfering RNA significantly reduced this supportive capacity. Our data suggest that mKirre is cleaved by metalloproteinases and that the extracellular domain of mKirre is responsible for supporting hematopoietic stem cells. These results contribute to our understanding of the mechanisms by which the hematopoietic microenvironment regulates hematopoiesis.     

Circulating bone marrow-derived osteoblast progenitor cells are recruited to the bone-forming site by the CXCR4/stromal cell-derived factor-1 pathway

Previous studies demonstrated the existence of osteoblastic cells in circulating blood. Recently, we reported that osteoblast progenitor cells (OPCs) in circulation originated from bone marrow and contributed to the formation of ectopic bone induced by implantation of a bone morphogenetic protein (BMP)-2-containing collagen pellet in mouse muscular tissue. However, the character of circulating bone marrow-derived osteoblast progenitor cells (MOPCs) and the precise mechanisms involving the circulating MOPCs in the osteogenic processes, such as signals that recruit the circulating MOPCs to the osseous tissues, have been obscure. In this report, we demonstrated for the first time that the MOPCs were mobilized from intact bones to transiently occupy approximately 80% of the mononuclear cell population in the circulating blood by BMP-2-pellet implantation. The mobilized MOPCs in the circulation did not express the hematopoietic marker CD45 on their surface, but they expressed CD44 and CXCR4, receptors of osteopontin and stromal cell-derived factor-1 (SDF-1), respectively. The MOPCs isolated from the mouse peripheral blood showed the ability to be osteoblasts in vitro and in vivo. Furthermore, the MOPCs in the circulation efficiently migrated to the region of bone formation by chemoattraction of SDF-1 expressed in vascular endothelial cells and the de novo osteoblasts of the region. These data may provide a novel insight into the mechanism of bone formation involving MOPCs in circulating blood, as well as perspective on the use of circulating MOPCs to accelerate bone regeneration in the future.     

RNA干扰抑制基质细胞衍生因子-1基因的表达

目的通过RNA干扰来抑制骨髓基质细胞衍生因子-1(SDF-1)的表达。方法利用脂质体介导人SDF-1特异性小片段双链RNA(siRNA)的表达质粒转染培养的人骨髓基质细胞,G418筛选阳性克隆。RT-PCR和ELISA法检测培养细胞SDF-1 mRNA和上清液SDF-1蛋白。以转染随机变更siRNA碱基序列的表达质粒和未转染的来源相同的骨髓基质细胞作为对照。结果较未转染和转染随机变更siRNA碱基序列表达质粒的骨髓基质细胞,转染SDF-1特异性siRNA表达质粒的骨髓基质细胞SDF-1 mRNA和SDF-1蛋白明显降低。结论用SDF-1特异性siRNA的表达质粒转染骨髓基质细胞,抑制了SDF-1基因表达。     

基质细胞衍生因子1对骨髓间充质干细胞迁移及皮肤创伤修复的影响

背景：基质细胞衍生因子1对骨髓间充质干细胞具有强烈的趋化作用,且基质细胞衍生因子1与骨髓间充质干细胞均能促进组织创伤愈合,然而有关两者与皮肤创伤愈合的研究文献报道较少。 目的：观察基质细胞衍生因子1在皮肤创伤修复过程中对骨髓间充质干细胞定向迁移及皮肤创面愈合的影响。 方法：选取30只SD大鼠随机分为5组,各组大鼠尾静脉注射PKH26标记的骨髓间充质干细胞,注射1周后于背部制作皮肤创伤模型,造模后于皮肤创伤处多点注射不同质量浓度的基质细胞衍生因子1(1,2,10,50 μg/L)。注射14 d后观察并记录大鼠皮肤愈合情况,免疫荧光染色观察创面组织骨髓间充质干细胞数量、分布情况,苏木精-伊红染色观察创面组织病理变化,Western blot检测创面组织Ⅰ型胶原及Ⅲ型胶原蛋白表达情况。 结果与结论：当基质细胞衍生因子1质量浓度为10 μg/L时,骨髓间充质干细胞在皮肤创面的数量最多,创伤修复效果最好。同样基质细胞衍生因子1能够调节Ⅰ型胶原及Ⅲ型胶原在创面的表达,基质细胞衍生因子1质量浓度为10 μg/L时,Ⅰ型胶原及Ⅲ型胶原表达最高。结果表明适宜质量浓度的基质细胞衍生因子1 (10 μg/L)能够更好地促进骨髓间充质干细胞迁移,从而促进皮肤创伤愈合。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Modulation of stromal cell-derived factor-1/CXC chemokine receptor 4 axis enhances rhBMP-2-induced ectopic bone formation

Enhancement of in vivo mobilization and homing of endogenous mesenchymal stem cells (MSCs) to an injury site is an innovative strategy for improvement of bone tissue engineering and repair. The present study was designed to determine whether mobilization by AMD3100 and/or local homing by delivery of stromal cell-derived factor-1 (SDF-1) enhances recombinant human bone morphogenetic protein-2 (rhBMP-2) induced ectopic bone formation in an established rat model. Rats received an injection of either saline or AMD3100 treatment 1 h before harvesting of bone marrow for in vitro colony-forming unit-fibroblasts (CFU-F) culture or the in vivo subcutaneous implantation of absorbable collagen sponges (ACSs) loaded with saline, recombinant human bone morphogenetic protein-2 (rhBMP-2), SDF-1, or the combination of SDF-1 and rhBMP-2. AMD3100 treatment resulted in a significant decrease in CFU-F number, compared with saline, which confirmed that a single systemic AMD3100 treatment rapidly mobilized MSCs from the bone marrow. At 28 and 56 days, bone formation in the explanted ACS was assessed by microcomputed tomography (μCT) and histology. At 28 days, AMD3100 and/or SDF-1 had no statistically significant effect on bone volume (BV) or bone mineral content (BMC), but histology revealed more active bone formation with treatment of AMD3100, loading of SDF-1, or the combination of both AMD3100 and SDF-1, compared with saline-treated rhBMP-2 loaded ACS. At 56 days, the addition of AMD3100 treatment, loading of SDF-1, or the combination of both resulted in a statistically significant stimulatory effect on BV and BMC, compared with the saline-treated rhBMP-2 loaded ACS. Histology of the 56-day ACS were consistent with the μCT analysis, exhibiting more mature and mineralized bone formation with AMD3100 treatment, SDF-1 loading, or the combination of both, compared with the saline-treated rhBMP-2 loaded ACS. The present study is the first that provides evidence of the efficacy of AMD3100 and SDF-1 treatment to stimulate trafficking of MSCs to an ectopic implant site, in order to ultimately enhance rhBMP-2 induced long-term bone formation.     

Enhanced wound healing by topical administration of mesenchymal stem cells transfected with stromal cell-derived factor-1

The objective of this study was to investigate the ability of mesenchymal stem cells (MSC) genetically engineered with stromal cell-derived factor-1 (SDF-1) to heal skin wounds. When transfected with SDF-1 plasmid DNA, MSC which were isolated from the bone marrow of rats, secreted SDF-1 for 7 days. In vitro cell migration assay revealed that the SDF-1-engineered MSC (SDF-MSC) enhanced the migration of MSC and dermal fibroblasts to a significantly greater extent than MSC. The SDF-MSC secreted vascular endothelial growth factor, hepatocyte growth factor, and interleukin 6 at a significantly high level. A skin defect model of rats was prepared and MSC and SDF-MSC were applied to the wound to evaluate wound healing in terms of wound size and histological examinations. The wound size decreased significantly faster with SDF-MSC treatment than with MSC and PBS treatments. The length of the neoepithelium and the number of blood vessels newly formed were significantly larger. A cell-tracing experiment with fluorescently labeled cells demonstrated that the percent survival of SDF-MSC in the tissue treated was significantly high compared with that of MSC. It was concluded that SDF-1 genetic engineering is a promising way to promote the wound healing activity of MSC for a skin defect.     

Stromal cell-derived factor-1/CXCL12 directly enhances survival/antiapoptosis of myeloid progenitor cells through CXCR4 and G(alpha)i proteins and enhances engraftment of competitive,repopulating stem cells

Stromal cell-derived factor-1 (SDF-1/CXCL12) enhances survival of myeloid progenitor cells. The two main questions addressed by us were whether these effects on the progenitors were direct-acting and if SDF-1/CXCL12 enhanced engrafting capability of competitive, repopulating mouse stem cells subjected to short-term ex vivo culture with other growth factors. SDF-1/CXCL12 had survival-enhancing/antiapoptosis effects on human bone marrow (BM) and cord blood (CB) and mouse BM colony-forming units (CFU)-granulocyte macrophage, burst-forming units-erythroid, and CFU-granulocyte-erythroid-macrophage-megakaryocyte with similar dose responses. The survival effects were direct-acting, as assessed on colony formation by single isolated human BM and CB CD34(+++) cells. Effects were mediated through CXCR4 and G(alpha)i proteins. Moreover, SDF-1/CXCL12 greatly enhanced the engrafting capability of mouse long-term, marrow-competitive, repopulating stem cells cultured ex vivo with interleukin-6 and steel factor for 48 h. These results extend information on the survival effects mediated through the SDF-1/CXCL12-CXCR4 axis and may be of relevance for ex vivo expansion and gene-transduction procedures.     

趋化因子基质细胞衍生因子1(SDF-1)及其受体CXCR4

趋化因子及其受体在免疫和炎症反应、造血以及HIV感染等方面发挥重要作用,其中基质细胞衍生因子-1SDF-1及其受体CXCR4由于在造血干细胞迁移、归巢以及HIV感染中的作用而受到关注,并对其作用机制进行了探讨,现就SDF-1及其受体CXCR4的有关内容作一综述。     

Malignant B cells from patients with primary central nervous system lymphoma express stromal cell-derived factor-1

Although the pathogenesis of primary central nervous system lymphoma (PCNSL) remains unclear, it is hypothesized that specific chemokine-chemokine receptor interactions may attract malignant B lymphocytes into the CNS. Formalin-fixed, paraffin-embedded brain biopsy specimens from 40 patients with PCNSL were immunostained by an indirect immunohistochemical method incorporating antigen retrieval to detect the presence of B-cell chemokines, stromal cell-derived factor-1 (SDF-1; CXCL12) and macrophage inflammatory protein-3alpha (MIP-3alpha, CCL20), and the SDF-1 receptor, CXCR4. To assist in phenotyping of SDF-1 + cells, specimens were also stained for CD20 (B cells). Positive staining for SDF-1 was identified in all PCNSL cases and in tonsil. In biopsy specimens, SDF-1 expression was localized to resident brain cells and, in 80% of specimens, CD20+ malignant lymphocytes. Tumor cells also stained positively for CXCR4. In contrast, although expression ofMIP-3alpha was detected in tonsil, no expression of this chemokine could be demonstrated in PCNSL biopsy specimens. Our observations raise the possibility of targeting the SDF-1-CXCR4 signaling pathway as a potential treatment for PCNSL.